1. Field of the Invention
The present invention relates to an interchangeable lens and a camera system that includes an interchangeable lens and a camera body.
2. Description of the Related Art
Japanese Patent Laid-Open No. (“JP”) 11-64956 discloses a camera system in which when an interchangeable lens is attached to a camera body, they communicate with each other for information exchanges and initialize a lens in parallel processing. The “initialization of the lens,” as used herein, means moving of a zoom lens or a focus lens to a predetermined position.
JP 11-94956 expedites booting-up of the camera system through the parallel processing, but the parallel processing requires the lens to be initialized before the information exchange between the interchangeable lens and the camera body is completed (or before the specifications and functions are mutually recognized). Thereby, several malfunctions may occur.
For example, when the initialization of the lens is started before powering-on of the camera is completed, the initialization of the lens may fail. In addition, if the initialization of the lens is earlier than expected or if the initialization of the lens is unnecessary, the lens starts an unintended operation and the camera system may become inoperable. Moreover, when the initialization of the lens and the boot-up of the camera body or other processing are simultaneously performed, the camera system runs short of power and the camera body may stop or is reset. These problems are likely to occur particularly when an interchangeable lens of a new specification is attached to a camera body of an old specification that does not support the new specification.